To learn about the origins of Ethernet, read this paper by Robert M. Metcalfe and David R. Boggs, which appeared in
"Communications of the ACM" in July 1976.
Visit the website of the IEEE 802.3 working group, that develops standards for CSMA/CD (Ethernet) based LANs, for the
latest developments. Most of the standards are also available at no charge in PDF format.
This article from PC Lube and Tune,
a Service Station and convenience store on the Information
Highway, located at Yale University is a good
introduction to the ethernet including some technical details. The
PC Lube and Tune site should be visited for
more interesting articles.
This website by the author of the book "Ethernet: The Definitive Guide" gives a more detailed desription of
the ethernet and links to other sources of information.